Desulphurized polysulphide polymer and process of making



I I Patented Mai- 31, 1942 imireo stars 1 strain I so PATENT QFHCTEDESULPHUR IZED POLYSULPHIDE POLYMER AND PROCESS OF MAKING .iosephi).Patrick, Morrisville, Pa, assignor to 'ihiokol Corporation, Trenton, N.5., a corpora-- tion of Delaware No Drawing.

Application September 18, 1940, Serial No. 357x n-elaims; (omen-79 Th1sinvention relates to organic polysulphide polymers and is acontinuation-in-part of my copending applications Serial No. 28,614,filed June 27, 1935, and Serial No. 168,522, filed October 11, 1937.

As set forth in my Patent No. 2,195,380,.issued May 26, 1940, and in mycopendingapplication Serial No. 267,389, filed April 12, 1939, theorganic polysulphide polymers (which may be produced by reaction betweenalkaline polysulphides and compounds containing two carbon atoms to eachof which is attached a substituent which is split oii during thereaction) are, generally, polymers of a unit selected from the groupwhere a. I I

represents two adjacent carbon atoms, and

I I -C...C-

where represents two carbon atoms separated by an joined to interveningstructure,

Generically therefore the polysulphide' polymers can be defined aspolymers of the units shown above.

The polysulphide polymers may be obtained by reaction between analkaline polysulphide and, generically, compounds having two carbonwhich is split, off during the reaction. Such a compound may have theskeleton carbon structure aim (where ALI}- I I represents-two adjacentcarbon atoms) or represents two carbon atoms joined to and separated byintervening structure). X and X are, generically, substituents split offduring the reaction.

(where Generically therefore these compounds can b defined as'having theformulas where the carbonatoms are adjacent and at (LX I A32 andrepresented by 3 to 6 sulphur atoms "having a formula Asatos) reactswith an oratoms to each of which is attached a substituent in themolecule (e. g., an alkaline polysulphide ganic compound having theformula XIHBX I I Kt $.10 I I as above defined the resulting polymerwill be substantially a polymer of the units In theequations andformulae written below is employed but it will be understood that in allthese cases the unit maybe substituted. There is no single acthe unit.ceptable arbitrary symbol covering both these skeleton structures andthe use of the symbol I I c I I l is therefore dictated purely by theabsence of suitable or acceptable chemical shorthand symbolism.

My Patent 2,216,044, dated September 24, 1940,

clearly points out the advance in the art represented by the interveninglinkage type of polymer over the adjacent carbon atom type. Thisinvention is directed to a generic technique of desulphurizationapplicable to polymers of both types generically or to polymers ofeither type specifically, after they have been produced.

Polysulphide polymers may be produced by other than the polysulphidereaction, for example, by reacting a compound having the formula ns-++snwith an oxidizing reagent, a polymer of the unit is obtained and byreacting this with elementary sulphur polymers of the unit may beproduced.

It has been discovered that saidipolymers of the unit of which carbonatom is attached a substituent split off during the reaction.

4. To react a desulphurizing agent with the polymeric reaction productof an alkaline polysulphide having the formula AS; to s and an organiccompound having two adjacent carbon atoms to each of which is attached asubstituent which is split off during the reaction.

5. To bring about the creation or development of new and improvedproperties as a result of the partial or complete removal of labilesulphur caused by the action of the desulphurizing agent.

a The invention is not limited to the application of a desulphurizingagent to a specific polymer .or class of polymers but extends to andincludes a generic chemical technique or mechanism for "removing labilesulphur from polysulphide poly-- mers generally.

That technique may be expressed by the sim-- ple equation I V [*i-f-Bsan +D i a; l +13 1 wi Nor is the invention confined to any specificdesulphurizing agent. The reaction is preferably carried out while thepolymer is dispersed in an "alkaline aqueous serum or dispersion mediumreact with desulphurizing agents according to This is owing to the factthat the sulphur of these polymers in excess of that corresponding tothe disulphides [At-psi] is in labile form and reacts readily with de-'sulphurizing agents or substances capable ofand when-so eflected, thedesulphurizing agent is preferably a water soluble alkalinedesulphurizing agent, e. g., an alkalinemonosulphide, hydrosulphide,sulphite, hydroxide, hydrosulphite,

'etc., but numerous other desulphurlzing agents I may be employed.

combining with sulphur and said labile sulphur is therefore capable ofbeing removed, in whole or in part.

It has further been discovered that this complete or partial removal oflabile sulphur causes' an improvement in physical properties, e. g.,elasticity and tensilestrength.

The objects of the invention therefore-include the following:

1. To react polymers of the unit" with a desulphurizing reagent.

2. To react polymers of the unit 7 with a desulphurizing reagent;

3. To react a desulphurizing agent with the polymeric reactionproduct-of an alkaline polysulphide having the formula AS: w c and anorganic compound having two carbon. atoms joined to and separated byintervening structure to each -March 26, 1940, respectively. p and 3 ofUnited States Patent No. 2,142,144 and 1 Examples 2, 4, '7 and 9 ofUnited States Patent No. 2,195,380.

The polymer both before and after the desulphurizing treatment ispreferably employed and obtained, respectively, in an intermediate formcapable ofbeing cured'by a subsequent curing reaction or heat treatment,as set forth, for example in my United States Patents No. 2,142,144 andNo. 2,195,380, issued January 3, 1939, and

The-principles and scope of the invention have been explained above andwill be defined in the claims. ii specific embodiment of said principleswill be illustrated by the following example:

Exampla-Into a closed reaction tank suitably equipped with stirringmeans, pipe coils for steam and cold water and a thermometer, are placed2,000 liters of 3-molar sodium tetrasulphide solution. To thepolysulphide solution are added with vigorous agitation, 10 kilograms ofcaustic soda dissolved in liters of water. This isfollowed-by theaddition of kilograms of crystallized magnesium chloride (MgChfiHaO)dissolved in 20 liters of water.

The polysulphide mix is heated to about F. and about 700 kilogram (5kilogram mols) of p BB dichlorethyl ether are added gradually over aperiod of about three hours. The rate of addition ofthedichloro ether isso regulated as to prevent the temperature from going above about 210 F.during the reaction.

to decompose the dichlor. ether may exert a'con- See Examples 2 tion andrepeated washing with water, or it may be washed by repeated settling ofthe particles and removal of supernatant liquid, followed byre-suspension in clean water and repetition of. the settling process.The washing produces a purified latex-like dispersion of the polymerwhich is now submitted to desulphurization as follows:

Add 250 kilograms (6.25 kilogram mole) of NaOH dissolved in,500 litersof water, raise the temperature to 212 F. and maintain there for about30 minutes. Then cool and purify the resulting latex as above described.

'The washed latex=lile dispersion may now be used as such or the polymerfrom which labile sulphur has been removed may be separated from thelatex by coagulation or evaporation of the water. Coagulation may beproduced by rendering the latex slightly acid. v y

In the above example the polymer prior to desulphurization, is a polymerof the unit and by the action of the NaOH at elevated tern peratures ischanged into a polymer of the unit As further specific examples, any ofthe organic compounds listed in Tables 1, 2, 3 and 4 in my United StatesPatent No. 2,195,380, on pages 3 and i of my United States Patent No.2,142,144,

and in my copending applications Serial No.

218,874, filed July 12, 1938, now United States Patent No. 2,216,044,and Serial No. 267,389, filed April 12, 1939, may be substituted for thedichlorethyl ether of the above specific example. Where X or X or bothare directly attached to an aromatic nucleus, the conditions under whichthe polymer is formed (prior to desulphurization) byv the polysulphidereaction should be more ethylene dichloride (and olefin dichiorides ingeneral.) Cl.CH2.CI-Iz.O.CH2.O.CH2.CH2.C1

di (beta chlor ethoxy) methane, or (11' (beta chlor ethyl) formaldehydeacetah CLCHaCHa.O.CH2.CH2.O.CH2.CH2.C1

di (beta chlor ethoxy) ethane, or di (beta chloro ethyl) ether ofethylene glycol, or beta chlor ethoxy chloro ethyl ether.

BB di (chloroethoxy) ethyl ether, or di beta chloro ethoxy) diethyleneglycol, or tetraethylene glycol dichloride.

The invention may be advantageously applied to polymers made bysubstituting for the specific.

ether in the above example compounds in genwhere R R, R and R are thesame or difbe cited to illustrate the utility of the present 111- eral'having one or more ether linkages such as those having the formula whereR and R are the same or difierent alka i,-

aralkyl or aryl radicals, ammo) inten ion .X'

ferent alkyl, aralkyl or aryl radicals,

' X. (R 0) .R .O.R ;X'

where R R and R are the same or diiferent alkyi, aralkyl or arylradicals,

where R R and R are the same or different agent and some or all of thelabile sulphur there- 7 by removed, the resulting product is found to begreatly improved in respect of tensile strength, elasticity and otherdesirable qualities, including the ability to withstand low temperatureswithout serious impairment of elasticity and strength. The improvementis particularly noted in the polymer when it is heated and cured andthus transformed from the intermediate stage to the final stage.Examples of compounds having more than two substituents, which may beused to make a polymer to be subjected to desulphurization are asfollows:

Ull.(.'-II2.C1 (1l, 2 trichlor ethane) crcnaclioicrucmol (1, 2, 4trichlor butane) C1.CH.CHC1.CHC1.CH9.C1 (l, 2, 3, lt'ctrachlor butane)(II-.IMCHZCIM (trichlor mcsitylcnc) and other compounds as set forth inmy copending application Serial No. 293,090, filed Sep tember l, 1939. i

Among the numerous instances which might vention and the advantagesflowing from its use the following may be mentioned: v

When an intermediate polymer made by reacting sodium tetrasulphide withBB dichlor ethyl ether is compounded with about ten parts by weight ofzincoxide and sixty parts by weight of carbon black and cured byheating, the rubber-like particles obtained which while possessingnumerous valuable properties including high resistance to a number ofsolvents-has a tensile strength of about 900 pounds per square inch Ifand an elongation at break of about 250%.

. now the labile sulphur is removed from saidin-i termediate polymerbefore curing and the result ing desulphurized or stripped polymersubjected I to the same cure, it will be found that the re-' sultingcured compound possesses a greatly increased tensile strength andelongation at break,

to wit: about 2,000 pounds per square inch tensile strength and about400 to 450% elongation at break. At the'same time the resistance to $01-highly desirable in synthetic rubber-like polymer Another markeddevelopment of new properties is illustrated by the iact that ii thestripped polymer, as for example in its cured condition,

.is employed to make a structure having a sur face which ii madeIromrubber would generate static electricity by friction and thelike,.the said structure does not develop static electricltyand iindsusein the manufacture of numerous articles for use where the generationof. static electricity is imdesirable, as for example; guides and rollsemployed in the textile industry-which come in contact with silk,cotton, wool, synthetic.

fibres. etc. This unique property is developed by the removal of thelabile sulphur and is characteristic of the disulphide polymers asdistinguished from the polymers having a higher sulphur rank,'that is tosay, a higher proportion of sulphur in the polymer. This particularaspect of the invention.is morev fully set forth in allowed applicationSerial No. 125,271, flled Febmay 11, 1937, now United States-Patent No.

2,218,176. I claim:

1. The process which comprises reacting a de- -'suiphurizing agent with'a substance which is substantially a polymer of a the group consistingof unit selected from and where represents adjacent carbon atoms and 1 irepresents carbon atoms separated by and Joined to interveningstructure.

2. The product which is substantially identi cal withthat obtainedlbythe process of claim 1.

3. The process which comprises reacting a desulphurizing agent with apolymer obtained by reacting an alkaline polysulphide having aproportion of sulphur representedby 3 to 6 sulphur atoms in the moleculewith an organic compound having two carbon atoms to each of amame whichis attached a substituent which is split oi! during the reaction. 7

4. The process which comprises reacting a desulphurizing agent with apolymer obtained by reacting an alkaline'polysulphide having aproportion .of sulphur represented by 3 to 6 sulphur 'atomsin themolecule with an organic compound having the formula ent-..

where i represents two carbon atoms joined to and sepa rated byintervening structure and X and X are substituents split of! during thereaction.

5. A product obtained by the process of V calim 4.

6. The process which comprises reacting a d desulphurizing agent with apolymer obtained by reacting an alkaline polysulphide with an organiccompound having the formula where ethyl ether.

9. The product substantially identical with that obtained bythe processof claim 8.

10. The process which comprises reacting a desulphurizing agent withthe. polymeric reaction product or an alkaline polysulphide having aproportion of sulphur represented by 3 to 6 sulphur atoms'in themolecule and B chloroethoxy B chloroethyl ether. 7

11. The product substantially identical with that obtained 'by theprocess of claim 10.

JOSEPH c. PATRICK.

